The dwindling visibility of tobacco products in prime time US TV drama programs may be linked to a fall in smoking prevalence of up to two packs of cigarettes per adult a year, suggests research published online in the journal Tobacco Control.

The impact may be as much as half of that exerted by pricing, say the authors.

In the largest study of its kind researchers watched and coded 1838 hours of popular U.S. prime-time dramas broadcast between 1955 and 2010 to gauge the impact of the depiction of tobacco products on smokers.

The trends were compared with smoking prevalence of cigarettes among US adults during this period.

The results showed that the depiction of tobacco, products, including smoking, purchasing, and handling, has fallen since 1961, in line with the decline in cigarette consumption.

TV tobacco use fell from 4.96 instances per hour of programming (excluding advertising) in 1961 to 0.29 instances per hour in 2010.

After taking account of changes in cigarette prices and other influential factors, the authors calculated that one less tobacco event per episode hour across two years of programming significantly predicted an annual fall of nearly two packs of cigarettes (38.5 cigarettes) for every US adult.

The price of tobacco is known to influence tobacco consumption. And the authors therefore compared the effects of price and TV depiction of tobacco on consumption.

They estimated that the declining visibility of tobacco on TV had half as large an impact in curbing consumption as price.

But importantly, the findings also suggested that continuing TV depiction of tobacco use may have hindered an even faster decline of the leading cause of preventable death in the United States.

The findings are consistent with other research showing that exposure to tobacco cues prompts cravings for cigarettes in adult smokers, say the authors.

The depiction of smoking in other screen media, such as cable TV and YouTube, should be studied further in the United States and internationally in countries with high rates of smoking and TV use, they conclude.